[Dangerous Doug]

You could offer the body preparation as an optioned upgrade like you do for the polished and 120 grit sanded finishes, but you'd need to make certain it is understood that there remains a great deal of body work to be done. Thus, you would have three body preparation options: prep'ed, sanded, and polished.

In terms of how much of a price reduction you should offer, you are actually the best to know: the "fair" reduction in price is a "fair" wage times the number of man hours required to prepare a body so that it is straight and requires no filling (pretty much what I assume you do now).

As for me, I'd want the body in pretty prestine shape, for I'd want to spend MY time sanding and polishing a straight body. If you reduced your "basic kit" to some price below $39k and then optioned it up to $39k for a "prepared body" that is the option I would go after.

I think an unprepared body would be interesting to a skilled body man, but I would guess that that is a small percentage of the Cobraphile population. That being said, is it worth the confusion that changing the attributes of your basic kit would cause? I would say most likely not.
Of course, I like Lew's idea of a good manual...

...Say "Hi" to Mary for me.

Regards,
Dangerous Doug